"eBay is committed to ensuring that no buyer is left out of pocket as a result of the unique nature of the event, and will ensure all buyers on the site can receive a full refund for their ticket purchase."

The online retailer will return sales commission to sellers when they refund buyers, eBay said.

Final details of how the exchange will work are to be announced next week.

Ticket retailer Seatwave and ticket exchange site viagogo both said they would also refund ticketholders.

But other retailers said they were unable to say at the moment what will happen.

A statement on Lastminute.com's website said it was working with AEG to provide its customers with information, and Ticketmaster said it was waiting for "official information".

Tony Northcott, of the Trading Standards Institute, said fans who are turned down for a refund but bought their tickets on a credit card should contact their card provider.

Jackson was due to perform the farewell concerts this summer, bowing out on an illustrious music career spanning several decades while aiming to restore his fortunes.

In March, tickets to his This Is It concerts at the O2 became the "hottest-selling on the planet", according to organisers, with 750,000 fans snapping them up.

Concert organisers said they were the fastest-selling tickets in London ever. They sold at a rate of 11 per second, 657 per minute and nearly 40,000 an hour with face prices of £50 to £75.